A 27-year-old man died shortly after his arrest in Kyneton on Tuesday, with police believing, at this early stage, that he may have ingested a substance.
Officers attended a Windridge Way property at about 2.30 pm as part of an investigation, where they arrested the 27-year-old.
Shortly after he became unresponsive.
Police immediately called for medical assistance and performed CPR on the man, however, he was unable to be revived.
The scene was cordoned off and guarded by police officers overnight.
Yesterday detectives were seen entering the property and seizing what appeared to be a computer and other evidence.
Five police officers who attended the scene were taken to hospital as a precaution.
Detectives from the Homicide Squad will investigate the incident with oversight from Professional Standards Command, as per standard practice when a person dies in police custody.
